First Lady Hillary Rodham Clinton yesterday urged Congress to approve additional gun-control legislation to prevent more shocking killings like those in Atlanta by a disgruntled investor.

Calling the murders of 12 people a “massacre,” Mrs. Clinton said: “I think it does – once again – urge us to think hard about what we can do to keep guns out of the hands of children and criminals and mentally unbalanced people …

“I would hope that the Congress would take action on the legislation that is now pending before it as soon as possible,” the first lady added.

Congress is considering gun-control measures that include requirements for background checks on all gun sales at gun shows and trigger locks to block kids from using guns.

But New York’s two biggest anti-gun crusaders said the Atlanta slaying wouldn’t have the same affect on the American gun debate as the Columbine HS rampage.

“Obviously what happened was a disaster, but my feeling is the person was mentally deranged and I don’t know if we could have stopped it,” said Rep. Carolyn McCarthy (D-L.I.).

“I’ve always said we can’t stop every killing. This is going to make people say, ‘What’s happening in this country that we’re having all this killing?'” said McCarthy, whose husband was killed and son wounded by a madman on the Long Island Rail Road in 1993.

McCarthy said gun advocates will point out that Mark Barton used axes and hammers, not guns, on some of his victims.

The difference, she said, is a person with a gun can “take an awful lot of people down in a short period.”

Sen. Charles Schumer (D-N.Y.), who also is pushing for strict gun-control laws, said the Atlanta shootings “remind people that guns are too prevalent and that Congress doesn’t have the guts to do something.”

But he also said: “Based on the facts that we know, this is not an incident in which gun laws would have stopped this man from getting a gun, because he had no record and the guns were not assault weapons.”